Nickel alloy/tungsten composite rod preparation method

Abstract

The invention provides a nickel alloy / tungsten composite rod preparation method, which comprises (1) subjecting a tungsten rod to surface cleaning treatment; (2) placing the cleaned tungsten rod and nickel alloy powder into a press mold, putting into a cold isostatic press, and pressing to give a nickel alloy / tungsten composite rod blank with nickel alloy porosity of 35%-45%; (3) vacuum sintering in a vacuum sintering furnace to reduce the nickel alloy porosity to be lower than or equal to 5%; and (4) drawing to obtain a finished product of nickel alloy / tungsten composite rod. The inventive method is simple in process, low in equipment investment, short in production cycle, free of pollution to environment, high in yield and capable of batch production. Nickel alloy in the nickel alloy / tungsten composite rod prepared by the inventive method has uniform thickness, low porosity and high finished product dimension precision, and the metal bonding rate of the nickel alloy and the tungsten rod is higher than or equal to 98%, or up to 100% after process optimization.

Description

technical field [0001] The invention belongs to the technical field of metal material processing, and in particular relates to a preparation method of a nickel alloy / tungsten composite rod. Background technique [0002] The power produced by nuclear power plant reactors is generally controlled by raising or lowering control rod assemblies in the reactor core. Fuel assemblies in modern reactor cores typically use two types of rod control assemblies to control reactivity, namely rod bundle control assemblies (RCCA) and gray rod control assemblies (GRCA). Both consist of a plurality of neutron absorbing rods secured at their top ends to a common hub or spider assembly. The rod body generally includes a stainless steel tube, which encapsulates neutron absorbing material. The commonly used black rod absorber material is silver-indium-cadmium alloy rod, and the absorbing material of the gray rod control component is stainless steel. [0003] According to the Chinese patent CN101...

AI Technical Summary

Problems solved by technology

[0004] At present, there are two main methods for the preparation of metal composite pipes: one is to use casting metallurgy technology, after the inner support pipe material is smelted, it is closely combined with the core rod material by casting method, and then the composite rod is prepared by cutting and grinding. The disadvantage of this method is that in the process of preparing nickel alloy / tungsten composite rods, due to the high melting temperature of nickel alloy (nickel alloy melting temperature> 1200 ℃), it is easy to cause recrystallization of tungsten material (recrystallization temperature> 1100 ℃), The strength of the core rod material decreases, resulting in the subsequent processing of the core rod is easy to break; another method is the sleeve and core rod composite method, that is, the tungsten rod is inserted into the nickel alloy sleeve, wherein the inner diameter of the sleeve is slightly larger than the outer diameter of the core rod. Then through the hard fit of the outer mold and the shrinkage, the outer metal sleeve and the metal mandrel are tightly combined to form a composite rod structure, such as a metal composite rod method described in Chinese patent CN03271518

The disadvantage of this method is that the dimensional accuracy of the core rod and the metal sleeve is high, especially for the thinner and long thin-walled pipe fittings, the inner diameter tolerance and straightness are higher, and the external mold and stretching are required in the subsequent processing. Hard fit, resulting in complex equipment structure, low lamination rate after product compounding